This invention is directed to a stretch-wrap film dispenser which can be manually operated to wrap a load, with the tension of the film during the wrapping operation being manually controlled by engagement of a digit over a brake ring.
When a plurality of packages are grouped together, it is desirable to combine them into a load, often of the size of a pallet so that the merchandise can be transported and stored in pallet-sized units. Stretch-wrap film can be wrapped around such a group to unitize the packages into a single load. The stretch-wrap film is a polymer sheet film of resilient nature and must be applied in the tensioned, stretched form in order to securely wrap the packages into a load.
The mechanical structures which relatively rotate the load with respect to the roll have tension control means thereon so that a constant tension is applied during the entire wrapping process. When fully mechanized, such constant tension is a desirable goal. However, when the roll is manually moved around the load being stretch-wrapped, conservation of the workers' energy is achieved by permitting the stretch-wrapped film to freely unroll while the worker moves down the side of a load. Tension is only applied as he swings the stretch-wrapped film around a corner. In this way, the major part of the material can be unrolled at little or no tension, and the tension need only be applied just before the film is moved around a corner of the package. With this manner of operation, the worker does not have to move against the tension at all times, to conserve his energy.
It is, thus, desirable to have a manually operable stretch-wrap film dispenser of such construction that the tension can be quickly and easily adjusted without moving the hands to a new position, and wherein tension control from zero to a fairly high tension can be achieved by the worker with a minimum amount of movement and/or physical force.
Two patents to John C. Parry, U.S. Pat. Nos. 4,179,081 and 4,248,392 teach the control of tension of unwinding plastic stretch film by clamping of a flexible sleeve onto the core which rotates with the roll of film. This is much like clamping a glove onto a rotating shaft, and does not produce substantial braking force for the amount of grasping force applied. In those structures, the braking is produced in much the same manner as in Dean U.S. Pat. No. 3,198,175. Other interesting prior art is shown in Partridge U.S. Pat. No. 521,245 which relates to a reel particularly adapted as a kite string holder for use in flying kites. It includes structure both for winding and unwinding of the kite string, including braking tension control during unwinding.